Brake system architectures are known for airplanes fitted with a plurality of brakes, such architectures including at least two braking computers, each capable of controlling all of the brakes.
Each computer is subdivided into two channels, a first channel being adapted to control the brakes while a second channel is adapted to monitor the first channel. If divergence should appear between the channels in the active computer, then the other computer automatically takes over, thus enabling that architecture to withstand a single breakdown.
Nevertheless, if a new breakdown were to occur on the second computer, braking using all of the brakes can no longer be guaranteed using those two computers only.
It is then necessary either to accept no braking, or to make do with degraded braking, or else to provide a third computer.